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Manuscript Title: GSAP: Fortran code for gamma-spectrum analysis.
Authors: V. Hnatowicz, V. Ilyushchenko, P. Kozma
Program title: GSAP
Catalogue identifier: ABRT_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 60(1990)111
Programming language: Fortran.
Computer: EC-1055 M.
Operating system: OS/360.
RAM: 128K words
Word size: 32
Keywords: Automatic peak detection, Doublet resolution, Gassian fit, Gamma-ray spectroscopy, Neutron activation Analysis, Fragmentation, Spallation, Fission, General purpose, Fit.
Classification: 4.9.

Nature of problem:
The program performs fully automatic detection and evalution of peaks in gamma-ray spectra measured with semiconductor detectors and stored in digital form.

Solution method:
Automatic peak detection is accomplished by convoluting the experimental spectrum with Gaussian second derivative digital filter. The sensitivity of the searching procedure may be chosen beforehand. The detected peaks are arranged into multiplets and corresponding fitting interval is found. Each multiplet is unfolded using standard non- linear least squares fit assuming Gaussian peak shape and linear back- ground. The number of free adjustable parameters may be chosen depending on the spectrum complexity and particular goal of the evaluation. The results are printed in concise form including statistical errors of the peak parameters. All quantities enabling one to judge the fit quality are also given. The result of the fit is presented in graphical form too.

Restrictions:
The dimensions, such as 4096 spectral points, are easily changed.

Unusual features:
The present program works in fully automatic mode. The only input parameters are the measured spectrum, its starting and final points, energy calibration, peak FWHM calibration and three parameters control- ing the peak search routine. The number of fitted peak parameters may be restricted. The restriction of the free parameter number is also performed automatically whenever the fitting procedure fails. In an extreme case, no least squares fit is performed and only first parameter guesses are given.

Running time:
On an EC-1055M compliation (H) takes 53 CPU seconds. A 4096 channel spectrum with 53 peaks is processed in 12 CPU seconds.